OEM Carrier Transformer 40VA 120V–24V for Model FX4DNF043T00ABAA

This OEM control circuit transformer (Part# HT01CN241) is the factory-specified replacement for the Carrier FX4DNF043T00ABAA air handler. The transformer steps down 120V line voltage to 24V AC, powering the entire low-voltage control circuit — including the thermostat, control board, contactor coil, and zone valves. When it fails, nothing in the system responds: the thermostat goes blank, the air handler won't energize, and the system appears completely dead even with power present at the unit.

• Specs: 40VA rated | 120V primary → 24V secondary | Compatible with standard low-voltage control wiring | Factory-matched output for stable board and thermostat operation
• OEM vs Generic: This is the exact OEM unit manufactured to Carrier's specifications. Generic transformers often carry inconsistent VA ratings and looser voltage tolerances, which can cause nuisance tripping of the control board or premature fuse failure — spending more in callbacks than the part itself is worth.
• Install difficulty: 2/5 — Shut off all power before servicing. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter (to confirm 24V output after install). Note existing wire connections before removal. Check and replace the 3A control fuse on the board if the transformer failed due to a short.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our stocked warehouse.

Compatibility: Designed for the Carrier FX4DNF043T00ABAA multi-position fan coil air handler. Always verify the transformer's VA rating and primary/secondary voltages on your unit's wiring diagram or data plate before ordering. If you're unsure of fitment, our HVAC parts team is available to confirm compatibility before you buy — no guesswork, no costly returns.